Materials containing alcohol alkoxylate have been used in a wide variety of industrial applications, for example as nonionic surfactants. They are typically prepared by the reaction of an alcohol with an alkylene epoxide such as ethylene oxide (i.e., oxirane) or propylene oxide (i.e., 2-methyoxirane) in the presence of one or more catalysts. Fluorinated alkylalkoxylates which are prepared by the reaction of an alcohol incorporating a fluorinated alkyl group with an alkylene epoxide are an important class of materials. Fluorinated alkylalkoxylates are especially useful in several industrial applications, including use as nonionic surfactants in various areas including the manufacture of polyvinylchloride (PVC) films, electrochemical cells, and various photographic and other coatings.
Known catalyst systems and processes for the alkoxylation of fluorinated alcohols include using Lewis acids such as boron trifluoride or silicon tetrefluoride, alone in combination with metal hydrides, fluorides, alkyls or alkoxides. Unfortunately, such acidic materials also catalyze side reactions such as dimerization of alkylene epoxides to form dioxanes during the alkylalkoxylation. The use of strong bases as catalysts alone is not satisfactory for alkoxylation of fluorinated alcohols.
U.S. Pat. No. 5,608,116 discloses a process for the preparation of fluoralkylalkoxylates in which a commercial mixture of perfluoroalkylethanols having the general structure RfCH2CH2OH wherein Rf is a linear or branched perfluoroalkyl group of up to 30 carbon atoms is alkoxylated in the presence of a catalyst system comprising an iodine source and alkali metal borohydride.
The fluorinated materials derived from long chain perfluoroalkyl groups having 8 or more carbons are expensive. Therefore, it is desirable to reduce the fluorine content through use of short chain fluorinated groups and partially fluorinated groups which can deliver the same or even better performance compared to the long chain perfluoroalkyl groups. The catalyst system disclosed in U.S. Pat. No. 5,608,116 is not satisfactory for alkoxylation of alcohols having short chain or partially fluorinated groups. This catalyst system suffers from low reactivity and poor reaction rates when alcohols having short chain or partially fluorinated groups are employed.
A process is needed using a catalyst system which provides desirable reactivity in the alkoxylation of alcohols having short chain or partially fluorinated groups. The present invention provides such a process and the resulting fluorinated alkylalkoxylates.